How CoolWallet uses SQD to secure its data back-end
Quick Facts
Description of CoolWallet: CoolWallet is the world's first mobile-native cold wallet, combining military-grade security with unprecedented convenience. Over 300,000 users globally are using its credit-card-sized hardware device to keep their private keys offline while connecting seamlessly through Bluetooth and NFC with their mobile device. All while maintaining a stellar security record and providing a smooth, intuitive transaction history experience across multiple chains.
Chains served: Bitcoin, Ethereum, multiple EVM chains, chains from the Substrate ecosystem, and TRON. In total, 35 + chains.
Make or break feature: Multi-chain support
Using SQD for: the entire transaction history pipeline.
Only possible with SQD: efficient batch synching across multiple native chains.
How CoolWallet discovered SQD
When building their wallet infrastructure, CoolWallet was faced with multiple challenges on the data front. One of the biggest was, naturally, the need to find a solution that was capable of retrieving data from the 35+ chains supported on CoolWallet.
“Our goal has always been to make crypto management intuitive yet secure, even for users without deep blockchain knowledge.”
After engineering the Secure Element chip used in CoolWallet in-house, the team had to implement custom blockchain signing logic themselves which provided full control over the security model but led to increased complexity when expanding chains supported.
To address this, they developed the CoolWallet SDK, which enabled external contributions, allowing for rapid expansion to new chains without compromising security. The team invested significant resources in making their wallet easy to use for everyone, hiding much of the complexity from end-users and adding features such as the Web3 Browser safety check, context-aware UI, and a consistent, clean interface.
Before discovering SQD, CoolWallet tried to run their blockchain nodes themselves to retrieve on-chain data, but quickly realized that it wasn’t a sustainable choice.
“This approach quickly proved to be unsustainable due to high infrastructure costs and the significant human resources required for setup, maintenance, and troubleshooting.”
The change to a third-party data provider lowered the cost but introduced new problems, such as inconsistent data models and rate limits. On the search for a more comprehensive, scalable indexing solution, they finally came across SQD.
SQD in CoolWallets’ data back-end
Requirements for a new provider included custom schema and parsing logic for flexible data processing, multi-chain support, efficient batch synching to handle high volumes, easy integration, and developer-friendly architecture.
“SQD's modular design, comprehensive documentation, and active community support made it the clear choice for our needs.”
Now, SQD is powering CoolWallet's entire transaction history pipeline, dealing with:
- Batch-fetching raw blockchain data
- Writing data to CoolWallet’s internal database
- Triggering downstream logic such as:
- User address filtering
- Token metadata enrichment
- Push notifications.
Once processed, the data is displayed to users via the mobile app, meaning that anyone who has ever used CoolWallet has likely interacted with data surfaced via SQD. This reflects CoolWallet’s long-standing commitment to delivering clear, consistent, and reliable transaction history as part of an intuitive user experience.
For further observability, the team also integrated SQD’s Prometheus metrics into their monitoring stack, providing them with real-time updates on the sync status and processor health.
Through the integration of SQD, the team achieved multiple goals, including:
- Real-time, trustworthy transaction history
- Reduced dependency and operational costs: by migrating to SQD, CoolWallet reduced its costs by 65% compared to a self-hosted setup while also reducing reliance on API providers.
- Increased control and transparency: The switch has also given them more control and transparency on what’s happening in their data backend.
On working with the SQD team
CoolWallet describes the initial setup with SQD as remarkably smooth and developer-friendly. They also welcomed the ability to implement additional customizations to optimize for their own production environment, such as custom retry mechanisms (handling network instability), node proxy layer for high availability, and enhanced monitoring.
Overall, they found our team to be an excellent partner.
“They are supportive, responsive, and open to feedback. Their documentation is clear, and they were quick to assist us with any integration roadblocks we encountered.”
All the quotes and feedback were kindly provided by the CoolWallet team. To learn more about what they’re building, check out coolwallet.io.